An electronic communication can be requested or initiated by one communication party with various levels of knowledge about the availability of an other communication party or parties:                1. In offline mode—e.g. by sending an email which will wait to be read by the recipient whenever she checks her email.        2. In a trial and error fashion—e.g. by placing a telephone call without knowing whether the called party is available and willing to take the call.        3. With presence information, that is by querying a “presence server” before issuing a communication request to obtain information relating to another party's availability and communication preferences. The information returned by this server may provide any of the following data, among others:                    Presence and availability—e.g. whether the receiver is logged in to one or more communication applications;            Current status—e.g. whether the receiver is willing to receive a communication, or does not want to be disturbed;            Communication preferences and access information—which communication channel and medium is presently preferred by the receiver for incoming communication request, e.g. fixed line or mobile number.                        
Presence servers are an integral building block of peer-to-peer (P2P) networks, where communication data—e.g. digitized voice, media, file attachments or other data—may be directly sent from one user to another, or from the source to the consumer. For this type of network, a presence server is necessary to determine how a communication partner can be reached—e.g. by returning the present IP address of the communication partner. The presence server may also offer other information related to a P2P network client, e.g. which files or which parts of files are available at the client for distribution.
P2P communication networks are effective for reducing central server load and server bandwidth requirements for such applications as distribution of copyrighted content (such as music, video, books, newspapers, software) that is charged upon use and protected by digital rights management (DRM), for distribution of open source software, point-to-point telephony and video conferences, among other uses.
Typically, a communication party may have several communication addresses or user identifiers, and a user may have presence information associated with or belonging to one or several user identifiers. Presence data may be associated with other user information or personal information. Since information on the presence and availability of a communication party is dynamic (i.e. may be updated regularly) management of presence data may present more challenges than managing other personal/user information.
As of now, most peer-to-peer networks are provided by proprietary and disparate frameworks, each with their own presence information server infrastructure and interfaces. Some applications—such as chat—have clients that can communicate with several frameworks. However, following up on every emerging new P2P framework and support its interfaces to allow inter-working of multiple networks would require significant effort and frequent client updates.
This means that potential users typically have to register for different identities with each kind of P2P network they want to use—e.g. Skype, another VoIP telephony application, a chat application and a social website with online interaction. Specific presence information—e.g. “Do not disturb, except in very urgent cases!”—has to be entered in every framework used. At any time, users have to think about which information about themselves they can and they want to publish in which network.
Because of this lack of interworking, unless users are willing to maintain identities and presence information for multiple networks, users tend to be tied to one application or a limited number of applications. Security may also be a concern. Early identity management approaches, such as Passport™ from Microsoft, have not been widely adopted, possibly because users were unwilling to expose so much of their personal information to a single global broker.
Thus, currently available systems have limitations with respect to managing or interrelating several identities, and managing presence and personal information in different application frameworks. Lack of authentication of users presents problems in managing presence information, for example, if user prefers not to share presence information with all other users, A user may not be able to verify the identity of other users before sharing presence information, or thus may not be able to control or select which other users may or may not have access to presence information.
A number of standards-based approaches exist for managing identity and presence information, for example:                1. The IP Multimedia Subsystem (IMS) by 3GPP. This requires an extensive unified architecture connecting the communication partners. It is believed that if at all, it will take decades, until this architecture is deployed with the majority of network operators and Internet Service Providers (ISP).        2. Electronic Numbering (ENUM) defined in RFC3761 is a specific approach designed for the interconnection of different telephony technologies based on telephone numbers.        3. Web Identity Management frameworks such as OpenID (www.openid.net), Prime (www.prime-project.eu), or Cardspace (www.cardspace.netfx3.com) may be used for identity, and dynamically, for presence information. However, it is not clear, at this time, how identities and associated information in these different frameworks can be searched and interrelated.        
Nevertheless, these solutions are not yet widely deployed, and interworking of different systems remains an issue. So, currently available approaches to managing presence and availability information for multiple applications or modes of communication in disparate frameworks have limitations, and improved or alternative solutions are required.